<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>loading03</title>
</head>
<link rel="stylesheet" href="../common.css">
<style>
    :root {
        --color: orange;
        --len: 25px;
    }

    .flex-wrap {
        flex-wrap: wrap;
    }

    .box {
        position: relative;
        width: 100px;
        height: 100px;
    }

    .square {
        height: var(--len);
        width: var(--len);
        background: var(--color);
        margin-right: 10px;
        flex-shrink: 0;
        opacity: 0;
        position: relative;
        top: 10px;
        animation: fall-in 6s infinite;
        animation-delay: calc(0.3s * var(--n));
    }

    .square:nth-child(3n+3) {
        margin-right: 0;
    }


    @keyframes fall-in {
        0% {
            opacity: 0;
        }

        5% {
            opacity: 1;
            top: 0;
        }

        50.9% {
            opacity: 1;
            top: 0;
        }

        55.9% {
            opacity: 0;
            top: 10px;
        }
    }
</style>

<body>
    <div class="box flex-row flex-wrap">
        <div class="square" style="--n:6"></div>
        <div class="square" style="--n:7"></div>
        <div class="square" style="--n:8"></div>
        <div class="square" style="--n:3"></div>
        <div class="square" style="--n:4"></div>
        <div class="square" style="--n:5"></div>
        <div class="square" style="--n:0"></div>
        <div class="square" style="--n:1"></div>
        <div class="square" style="--n:2"></div>
    </div>
</body>

</html>